[scottybaccus]

A little more info...

The ECM uses the two wire sensor to modify a 5 volt reference signal. It only means anything to the ECM. Your gauge has voltage applied to the gauge, and then gets a ground through the sensor, which provides a variable resistance to move the needle around. I laid one wire alongside the LS harness, from the sensor, to the back of the motor, and spliced it into the factory temp sensor wire, then I swapped the sender for the three wire unit from a '98 Camaro. (I'll confirm that) I cut the connector off the harness and replaced it with the 3 wire pigtail. The blue wire on the pigtail connects to your original gauge extension, the other two go to the LS harness, and it isn't important which is which, but colors should match, anyway.

Part numbers:
sensor- 12551708, TU280, TX111 or 1T1081, $15-$25
pigtail- 1P1065, S619 or PT2319, $15-$30

I have found this works great on my '87's factory gauge. It hits the 1st line at 1/3 scale at 200*. That's pretty much where it stays.